Process for polymerizing unsaturated monomers with dilithium organosilane oligomers

ABSTRACT

DIENE AND VINYL MONOMER POLYMERIZATION CATALYSTS CONSISTING OF DILITHIUM ORGANOSILANE OLIGOMERS REPRESENTED BY   LI-(CH2-CH(-SI(-R)3))N-LI   WHEREIN R DENOTES THE SAME OR DIFFERENT C1-C10 ALKYL RADICALS, OR ALKL RADICALS OR ARYL RADICALS, AND N IS AN INTEGER FROM 2 TO 30. THE CLAIMED CATALYSTS ARE USEFUL FOR POLYMERIZING DIENE AND VINYL MONOMERS IN HYDROCARBON MEDIA UNDER HOMOGENEOUS CONDITIONS. THE PROCESS MAY FIND APPLICATION IN THE SYNTHETIC RUBBER INDUSTRY.

Oct. 30, 1973 N. S. NAMETKIN ET AL PROCESS .FOR POLYMERIZING UNSATURATED MONOMERS WITH DILI'I'HIUM ORGANOSILANE OLIGOMERS Filed Aug. 13, 1970 Y '2 39 6992 I PROCESS 'FOR POLYMERIZING UNSATURATED .-MONOMER S-WITH DILITHIUM; ORGANOSILANE -.-OLIGQMERSJ1. 1 v Nikolai sergeevic h blametkin, Leninsky prospekt 13, kv. ,11; Serge Gari'evich Durgarian', ulitsa Garibaldi 21, Qkorpus 3, kvf.'f, ,67;' Vadirn Ivanovich Kopkov, ulitsa j zelenogradskayafls,"korp'us 2, kv. 194; Valery Samuilo- 'vicll f'jKhotinisky, "Ko'nkov'o-Dereylevo, 1 miqroraion, korpusj7, l rv. -'l'47;i"and' lrina Sergeevna Bryantseva, L'eninsky prspekt'69ykve-83, an'or Moscow, U.S.S.R.; tnand' GennadyiNikolaevich Petrov, Zheleznodorozhny -npereulokvfl, 35; v,Gennady Mikhailovich Tolstopyatoy,-'B, ,ulyar NoyatorovBS, ,kv.' 146; Tatyana Vladiv :lnirovna Stadniclrulr,,prospekt Kosmonavtov 48, kv. 110'; Tatyana .Alexe'evn'a" Kornilova, Tallinskoe shosse 4'8,"k'v: 55;and' Anna Berkoyna Shoikhet, Varshavskaya ulitsa.6, kv 111, all of Leningrad, U.S.S.R.

FiledAug.I13, 1970,' Sen No. 63,517 ''Claims priority, application U.S.S.R., Aug. 13, 1969,

I =..1358104- 1 Int.-Cl.,C08 1/28, 7/04 ei; 130, re. a

10 Claims THELDIS CLOSURE Diene and-vinyl monomer polymerization catalysts consisting of dilithium organosilane oligomers represented by bet industry. a 4

This invention relates to -the synthesis of high molecular weight compoundsby, polymerization and, more particpolymer chain, so thatinfrnany' instances the desired rate of producing the polymers having the requisite molecular .weight cannot b'eaa'ainem To overcome this disadvantage, it was suggested to emvploy dilithium, catalystswhich,provide for polymer chain growth siinnltaneously atb th chainends, thereby making it possible, theconcent n "of lithium being the same, to obtain thepolymer I a higher irnolecular weight than thoseprepared'th'rough the "use of 'nionolithium .cata

lysts, or else .tq redu c eby one half the time required for I preparation-0f polyme'rof a given molecular weight. A

further 'advanta'geof dilithium catalysts is associated with lower susceptibility of the number of growing chains to the presenc impurities; capable'fof poisoning organolithium co'rh ounds; since withanactive center inhibited I 3,769,266 Patented Oct. 30, 1973 at one end of the chain, chain growth at the other end remains unaffected.

The known organodilithium catalysts such as, for example, dilithium naphthalene, dilithium stilbene, etc., are insoluble in hydrocarbon media (in bulk hydrocarbon monomers and hydrocarbon solvents), which are preferably used for carrying sterospecific polymerizations and copolymerizations. Hence, polymerizations in the presence of the known organodilithium catalysts are necessarily heterogeneous processes and as such cannot be accomplished in a facile and convenient manner and, moreover, allect adversely the quality characteristics of end products. It is an object of the present invention to provide a polymerization process which can be carried out under homogeneous conditions in a hydrocarbon medium and in the presence of dilithium catalysts.

It is another object of the present invention to provide organodilithium compounds soluble in a hydrocarbon medium and capable of catalyzing the process of diene and vinyl monomer polymerization.

We have found that these objects are accomplished by the provision of hydrocarbon-soluble organodilithium catalysts comprised ofthe heretofore unknown dilithium organosilane oligomers having the general formula dilithium oligovinylbenzyldimethylsilane and diluthium oligovinylphenyldimethylsilane In the aforesaid oligomers n is an integer of from '2 to30.' "The compounds specified herein before are oligomers which are readily soluble in organic solvents such as, for "example, benzene, toluene, pentane, hexane, heptane,

octanefdecane, cyclohexane and other'aromatic,aliphatic or cycloaliphatic hydrocarbons or mixtures thereof,zether's such as, for example, diethyl ether and dibutyl ether,. and tertiary amines such as, for example, tr'iethyla'mine.-

- Said oligomers are prepared by reacting vinyltriorganosilanes of the general formula I t R-si-R wherein R denotes the same or diiferent alkyl radicals having from 1 to 10 carbon atoms, aryl or substituted aralkyl radicals, with lithium metal at a temperature of from to 100 C., preferably from 25 to 60, in an atmosphere that is chemically inert towards organolithium compounds, e.g. under argon, helium, etc., or in vacuo at a residual pressure of down to 10- mm. Hg.

Lithium may be used in the form of a suspension, small pieces, or a mirror on the reaction vessel walls.

The vinyltriorganosilane-to-lithium ratio (mole/gramatom) should be in the range of 1:3 to :1, preferably from 1:2 to 2:1.

The present invention also consists in a method of polymerizing diene and vinyl monomers which comprises subjecting diene or vinyl monomers to polymerization in the presence of dilithium organosilane oligomers of the general formula given herein before.

The present method of polymerizing diene and vinyl monomers under the effect of the catalysts, according to the invention, may be practiced in different ways. For example, the process may be carried out in the monomer bulk or in organic solvent media, hydrocarbon solvents inclusive, such as pentane, hexane, heptane, nonane, decane, cyclohexane, benzene, toluene, etc., or in mixtures of said solvents.

Depending upon the monomer used, the process temperature may be varied from --50 to +150 C.

Insofar as the process of polymerization in the presence of organolithium compounds is susceptible to diverse impurities such as, for example oxygen, water, alcohols, etc., use is made of dry, high purity monomers.

Polymerization can be conducted in vacuo under a residual pressure down to 10- mm. Hg or in an atmosphere that is chemically inert towards organolithium compounds, e.g. under methane, argon, helium, and the like.

The catalyst-to-monomer molar ratio lends itself to variations within a wide range depending upon the soughtfor molecular weight of the polymerization product. With the catalyst-to-monomer molar ratio varying from 1:15 to 1:10,000, it is practicable to obtain both low and high molecular weight products.

When the reaction mixture contains a high proportion of the catalysts, the reaction yields oligomers which may find application in diverse syntheses such as, for example, preparation of dicarboxylic acids, diols, diamines, etc. High molecular weight products are obtained in case the catalyst-to-monomer molar ratio in the reaction mixture is low, e.g. from 1:500 to 1: 10,000.

The employments of oligomers of the present invention as catalysts makes it possible to effect the polymerization of a broad range of diene and vinyl monomers such as, for example, butadiene, isoprene, styrene, substituted styrenes, methyl methacrylate, vinyltrimethylsilane, vinylphenyldimethylsilane, vinylethyldimethylsilane, vinylbutyldimethylsilane, and the like.

The employment of hydrocarbon-soluble dilithium derivatives of organosilane oligomers as catalysts in diene and vinyl monomer polymerizations makes for a substantial facilitation of polymerization process control, for example, by dosaging accurately the catalyst solution in order to provide appropriate conditions for the preparation of polymers having the desired molecular weights.

Catalyst solubilityin the reaction medium is conducive to. carrying'out homogeneous polymerizations which offer advantages as far as the manufacturing equipment and process simplicity are concerned.

The catalysts of the present invention are useful for conducting the stereospecific polymerization of conjugated diene monomers and vinyl monomers in a reaction medium consisting of hydrocarbon solvents such as, for example, hexane, heptane, benzene, toluene, and cyclohexane.

For a better understanding of how the present invention may be practiced, the following examples are given by way of illustration with reference to the accompanying drawing which shows the apparatus for synthesizing and metering out the catalysts.

EXAMPLE 1 Synthesis of dilithium oligovinyltrimethylsilane The reaction is carried outin' the glass apparatus shown in the drawing. The apparatus via outlet tube" 1 issealed to a vacuum unit capable of producing'a vacuum of 1x 10- mm. Hg and evacuated for a period of '48 hours, followed by disconnecting the apparatus from 'thevacuum unit and filling it with dry andpure argon. Next; 0.5 g. (0.06 gram-atom) of lithium dispersed in parafiin isintroduced in a stream of argon via'inlettube 3 intoampoule 3. Inlet tube 2 is next sealed OfLand-the apparatus is connected to the vacuum unit in order to condense. via outlet 1 into ampoule 3 vinyltrimethylsilane (17.7 g.; 0.177 mole) and cyclohexane ('100 inl.). The apparatus is sealed 01f the vacuum unit at points a and b and placed in a thermostat. g J

The reaction is carriedout for a period of, 24 hours at 25 C. The resultant solution is filtered through a sintered glass funnel (G-5.4) andplaced in ampoules 5.

In the resultant solution of the organodilithium compound, the concentration of lithium equals 049 gramatom per liter.

The oligomer thus prepared has a-molecular weight of 960 (according to cryoscopic measurements), the degree of polymerization being nE9.

EXAMPLE 2 Synthesis of dilithium oligovinylbenzyldimethylsilane Employing the apparatus and the procedure described in Example 1, dilithium oligovinylbenzyldimethylsilane is prepared from 7.1 g. (0.04 mole of vinylbe nzyldimethylw silane and 1 g. (0.14 gram-atomy o'f lithiumlin 40m L-of decane. The reaction is carried out for2 4 hours at, C.

In the resultant solutiomof the organodilithiumcompound, the concentration of lithium equals 1 gram-atom per liter.

The molecular Weight of thedilithium oligovinylbenzyl- ((limethylsilane determined cryoscopically equals 350 .EXAMPLE 3 Synthesis of dilithium o1igovinylphenyldimethylsilane Employing the apparatus and the procedure described in Example 1, dilithium oligovinylphenyldimethylsilane' is prepared from 8 g. (0.05 mole) of vinylphenyldimethylsilane and 1.1 g. (0.15 gram a'to'm) of lithium'in 50 ml. of benzene. The reaction is carried out for 18 hours at 00 C- In the resultant solution of the organodilithium compound, the concentration of lithium equals 0.6 gram-atom per liter. i g Y The molecular weight of the'dilithium oligovinylphenyldimethylsilanethus prepared equals 4,500, 'so' that the degree of polymerization, n, is ca. '30.

EXAMPLE 4 Synthesis of dilithium oligovinylamyldimethylsilane Employing the apparatus and the proceduredescribed in Example 1, dilithium oligovinylamyldimethylsilane is prepared from 13,7f'g. (0.1 mole) of vinylamyldim ethyk silane and,0.07 g. (0.01 gram-atom) o'f'lithium in' 50 ml. of hexane. The reaction is carried out for 48 hours at 40 C. .-a' v I.

In the resultant solution of the organodilithium compound the concentration of lithiumiequalsl grain-atom per liter. f j

The molecular weight of the joligomermeasured bythe crycgsfgaic method equals 580' (degree of polymerizat i on EXAMPLE 5 Polymerization of divinyl (a) In a 1-l. reactor fitted with a stirrer and filled with argon are charged in a stream of dry, pure argon 130 ml. of divinyl, 500 ml. of toluene, and ml. of a toluene solution of dilithium oligovinyltrimethylsilane (lithium concentration in the solution, 0.05 gram-atom per liter). The polymerization is conducted for a period of 4 hours at a temperature of 60 C., the yield of polydivinyl being 82%.

Intrinsic viscosity (in benzene) equals 3.2 dL/g.

Polymerizations of isoprene, 2-methylpentadiene-1,3,2, 3-dimethylbutadiene and cyclopentadiene are carried out by following the above procedure.

(b) In a H. reactor fitted with a stirrer and filled with argon are charged 200 ml. of divinyl, 500 ml. of cyclohexane, and ml. of the dilithium oligovinylbenzyldimethylsilane solution prepared in accordance with the procedure of Example 3. The reaction mixture is maintained in the reactor for 4 hours at 55-60 C., followed by cooling the reaction mixture down to C., introducing 3.0 g. of propylene oxide into the reactor, and continuing the reaction for an additional 2 hours at a temperature of 20 C.

In the polymer separated by treating the reaction mixture with water, the content of hydroxyl groups equals 1.30% by weight. The molecular weight of the polymer determined by the cryoscopic method equals 3,500.

EXAMPLE 6 Polymerization of vinyltrimethylsilane A sealed ampoule containing 2 ml. of a dilithium vinyltrimethylsilane solution (lithium concentration in the solution, 0.5 gram-atom per liter) is placed in a H. ampoule fitted with a metallic ampoule breaker. The larger ampoule is connected to a vacuum unit, evacuated for 24 hours in order to remove the traces of moisture from the inner walls, and thereafter charged with 500 g. (5 moles) of dry and pure vinyltrimethylsilane by recondensation in vacuo.

The ampoule is sealed OE and, after breaking the catalyst-containing ampoule, placed in a thermostat, in which it is maintained at 40 C. for a period of 200 hours.

The yield of polyvinyltrimethylsilane equals 76%.

Intrinsic viscosity (in cyclohexane at C.), 1.8 dl./g.

EXAMPLE 7 Polymerization of vinylphenyldimethylsilane Polymerization is carried out by following the procedure described in Example 6.

320 g. (2 moles) of vinylphenyldimethylsilane and 2 ml. of a benzene solution of dilithium oligovinylphenyldimethylsilane (lithium concentration, 1 gram-atom per liter) are maintained at 25 C. for a period of 100 hours, the yield of polyvinylphenyldimethylsilane being 80%.

Intrinsic viscosity (in toluene at 25 C.) 1.2 dL/g.

EXAMPLE 8 Polymerization of styrene Polymerization is carried out by following the procedure described in Example 6.

50 g. (0.5 mole) of styrene, 100 ml. of diethyl ether and 100 ml. of cyclohexane in the presence of 2 ml. of a cyclohexane solution of dilithium oligovinylbenzyldimethylsilane (lithium concentration, 1 gram-atom per liter) as initiator are maintained at 20 C. for a period of 4 hours.

The yield of polystyrene equals Intrinsic viscosity (in benzene at 25 C.), 0.8 dl./ g.

EXAMPLE 9 Divinyl-styrene copolymerization In a 0.5-l. reaction vessel fitted with a stirrer are charged, in a stream of argon, 65 ml. of divinyl, 33 ml. of styrene, 400 ml. of toluene, and 1.5 m1. of the dilithium oligovinylbenzyldimethylsilane prepared as disclosed in Example 3.

Copolymerization is carried out for a period of 8 hours at 60 C., the yield of the copolymer being 86%.

Intrinsic viscosity (in benzene at 25 C.), 1.35 dL/g.

What we claim is:

1. A process for polymerizing monomers selected from the group consisting of conjugated dienes having 4 to 6 carbon atoms, styrene, methyl methacrylate, vinyltriorganosilanes wherein at least two of the three organo groups are methyl radicals, and mixtures thereof, which comprises contacting said monomers in the bulk or in organic solvent and at a temperature of from 50 to C. with dilithium organosilane catalysts, the catalyst-to-monomer molar ratio being within the range of from 1:15 to 1110,000, said catalyst consisting of dilithium organosilane oligomers represented by the general formula wherein R denotes the same or dilferent C -C alkyl radicals, aralkyl radicals or aryl radicals, and n is an integer from 2 to 30.

2. A process as claimed in claim 1 wherein polymerization is carried out in a hydrocarbon solvent medium selected from the group consisting of paraffinic, aromatic and cycloaliphatic hydrocarbons and mixtures thereof.

3. A process as claimed in claim 1, wherein the catalyst-to-monomer molar ratio is in the range of from 1:500 t0 1: 10,000.

4. A process as claimed in claim 1, wherein polymerization is conducted in vacuo under a residual pressure of down to 10* mm. Hg.

5. A process as claimed in claim 1, wherein polymerization is carried out in the atmosphere of a gas that is chemically inert towards organolithium compounds.

6. The process as in claim 1, in which the catalyst is dilithium oligovinyltrimethylsilane.

7. The process as in claim 1, in which the catalyst is dilithium oligovinylphenyldimethylsilane.

8. The process as-is claim 1, in which the catalyst is dilithium oligovinylbenzyldimethylsilane.

9. The process as in claim 1, wherein n is an integer from 2 to 10.

10. The process as in claim 1, wherein said vinyltriorganosilane is selected from the group consisting of vinyltrimethylsilane, vinylphenyldimethylsilane, vinylethyldimethylsilane and vinylbutyldimethylsilane.

References Cited UNITED STATES PATENTS 2,811,541 10/1957 Curry 260--80 3,324,089 6/ 1967 Trepka 260-80 JAMES A. SEIDLECK, Primary Examiner US. Cl. X.R.

260-82.l, 83.5, 83.7, 89.5 A, 93.5 S, 94.2 M, 448.2 R 

